Method of manufacturing thermostatic devices



P. R. LEE

Oct. 14, 1941.

METHOD OF MANUFACTURING THERMOSTATIC DEVICES Filed Jan. 12,. 19:59 3 sheets-Sheet 1 Q INVENTOR a/Xidee.

WITNESSES:

P. R. LEE

Oct. 14, 1941.

METHOD OF MANUFACTURING THERMOSTATIC DEVICES Filed Jan. 12, 1939 5 Sheets-Sheet 2 INVENTOR fyZ/Qiea Af QRNEY P. R. LEE

Oct. 14, 1941.

METHOD OF MANUFACTURING 'THERMOSTATIC DEVICES Filed Jan. 12, 1939 3 s ets-Sheet 3 INVENTOR /@W//PZ6.

WITNESSES:

ATTORNEY f rom such description.

Patented Oct. 14, 1941 UNITED STATE s PATENT OFFICE METHOD or MANUFACTURING THERMOSTATIC DEVICES Paul R. Lee,

Mansfield, Ohio, assignor to Westinghouse Electric & Manufacturing Company,

., a corporation of Penn- East Pittsburgh, Pa sylvania Application January 12, 1939,

Serial No. 250,538

4 Claims. (Cl. 29-148) My invention relates to bimetallic thermostats, and more particularly to the method of manufacturing bimetallic members therefor.

An important well-known step in manufacturing a snap-acting bimetallic member, in addition and thus to raise the snapping temperatures of such member to a given predetermined value. However, this operation raises both the opening and closing temperatures of such member. Accordingly, the forming operation was introduced to provide the desired diflerential between the opening and closing values; namely, by lowering the closing and raising the opening temperature value. The two-step operation of the prior art, while to a small degree producing the desired operating characteristics in a bimetallic member, has been quite expensive and uncertain in its results. Furthermore, such operations do not readily lend themselves to mass-production methods, and at the same time, desired control-over the exact setting of the operating limits of the membe l V It is, therefore, an object of myinvention to provide a method of forming a bimetallic member which, while lending itself very favorably to mass-production methods, eliminates the need of following the common practice of cooking the member in clamps.

A further object of my invention is to provide a method of forming abimetallic member at room temperature which simultaneously determines the snapping temperature and the differential between the opening and closing temperatures of such member.

Other objects of my invention will eitherbe pointed out specifically in the course of thefollowing description of a method of forming my device embodying my invention, or will be apparent In the accompanying drawings: I Figure l is a perspective view of a blank sheet of bimetallic material;

Fig. 2 is a perspective view of a thermostatic device or element punched from the blank sheet;

Fig. 3 is a side elevational view of the bimetallic member andmounting device;

Fig. 4 is a side elevational view of the lie device in its final form;

Fig. 5 is a top plan view of a mechanical debimetaldo not afford the formation device which may be employed in my invention;

Fig. 6 is a view, in elevation, taken 5; and

Fig. 7 is a perspective'view of a mass production mechanical deformation device used in manufacturing the bimetallic members in acpartly in section and partly along the line VI-VI of Fig.

' cordance with the teachings of my invention.

Referring to the accompanying drawings, I illustrate a method of producing a snap-acting bimetallic or composite heat-responsive member which is formed by suitably stamping or punching a blank sheet of bimetallic material ill to form a bimetallic link l2 having a central strip I6, and then mechanilink l2 so as to produce a predetermined general curvature of the link and to crimp the lateral strips thereof.

'More specifically," the bimetallic link 12 in cludes the central strip l4 and two lateral strips l6 which are formed by means of laterally positioned elongated slots l1, and transverse end 'portions l9. A circular aperture l8 may be posi-,

tioned within an end portion I9 and extend somewhat into the central strip ll, or such aperture may be totally within the'central strip l4 and near the end portion l9. Moreover,-it is to be understood that the aperture l8 may be positioned elsewhere if desired.

The bimetallic link I2 is formed of a suitable composite or bimetallic heat-responsive material which will change its shape with a change in temperature thereof in a predetermined manner. A

mounting rivet 20 is rigidly attached to the bimetallic link I2 through the aperture 18. The rivet 20 extends, in this instance, along the central strip I4 and affords means for rigidly mounting the bimetallic member I! after having been formed, as hereinafter described, to any suitable support 7 ing structure (not shown). The exact method of mounting the bimetallic member I2 is more clearly described in a co-pending application,

Serial No. 225,354, filed August 17, l938, assigned to the assignee of this application.

' Referring to Figs. 5 and 6, I show a hand-operated mechanical deformation device 22 comprising a supporting structure 24, a plurality of discs 26a and 26b having adjustable teeth 28 located thereon, and an adjusting rack 30 movably positioned upon the supporting structure 24 and directly associated with the discs 26b. The supporting structure 24 is, in this instance, substantially a U-shaped metallic member :having a plurality of apertures 32a and 32b positioned within .2 and along the longitudinal axis of the top portion v-thereof and a threaded shaft or screw 84 rigidly attached at one end thereof.

The adjusting rack 88 is positioned upon the top surface of the supporting structure 24 and bass plurality of apertures 88a and 88b located therein which are substantially in line with the apertures 82a and 82b, respectively, in the supporting structure 24. The adjusting rack 88 has a depending end portion 88 located at one end thereof. An aperture 40 is located within the de-.

pending portion 88 and cooperates with the adjusting screw or shaft 84. An adjusting nut 42 is rotatively associated with the depending portion 88 of adjusting rack 88 and is threadedly engaged with the screw or shaft 84. The rack 88 may then be moved longitudinally with respect to the supporting structure 24 by merely rotating The discs 26a and 26b are positioned upon the the adjusting nut 42.

"adjusting rack 88 in line with the apertures 32a and 82b, and 88a and 86b, respectively, and have ,apertures .44 located substantially at the midpoints thereof. Shoulder screws 48a and 46b arepositioned through the discs 26a and 26b,

respectively, and thecorresponding apertures 44,

' {8811 or 881; and 32a or 32?), respectively, to provide tially flxedin its position with respect to the adjustingrack 88 arid movable with respect to the supporting structure 24.v inasmuch as there is substantially a, tight fit between the adjusting rack and the bolt 46b. The aperture 32b, in

supporting rack 24, is considerably larger than the bolt 48b and aperture 38a in adjusting in rack 88, .is considerably larger than .bolt 48a.

88 may be moved with respect to support 24and disc 28b will move simultaneously with the move- ,me ts of the adjusting rack 80, while disc 26a will remainin substantially a fixed position. In other words, as the adjusting nut 42 is rotated, the relative position between the disc. 28b and disc- 28a will be adjustably varied for apurpose hereinafter described.

The. teeth 28 are adjustably positioned upon the discs 28a and 28b by means of suitable set screws 82. The set screws are rigidly attached 1 to the discs 28a and 28b and are inserted through slotted apertures 58 in the teeth 28. Accordingly,

it is obvious that the teeth 28 may be adjusted with respect to the corresponding discs. 28a and 28b, or in other words, the pitch of the meshing teeth 28 may be adjustably varied with respect to.

the position of the axes of therespective discs 28a and. 28b. It is. therefore, obvious that the discs 28a and28b may be adjustably separated and that the teeth 28 may be adjustably positioned with respect to eachother and to-the ,cor-

- responding discs 28a and 28b.

.The mechanical deformation device 22 may be used to mechanically deform the bimetallic link I2 at room temperaturesubstantially as follows. The link I2, including the rivet 20 located thereon, may be positioned upon the device 22 with one endthereof engaging the cooperating teeth 28. 'Thediscs28a and 28b are then rotated by means of suitable handles. 21 so that the bimetallic member I2 will be drawn therebetween. The teeth 28 will then engage, in this instance, only the lower lateral strip I8, causing the bimetallic I2 through the rotating teeth in a reverse direction, it is obvious that the previously determined over-all curvature of themember I2 will be' maintained, and the crimps formed in the second lateral strip will be substantially the same as those in the first strip. In other words, both the.

lateral strips I8 will then be correspondingly mechanically deformed and, bimetallic member I2 willthen be simultaneously forced into a general curved shape, as shown in Fig. 4.

It is obvious that the mechanical deformation device 22 as hereinabove described, simultaneously subjects the one and then the other of the Y lateral strips of the member I2 to a mechanical crimping deformation and produces a general curvature in the bimetallic member I2 at room temperature. However, it is obvious that the device 22 will be somewhat slow in its operation inasmuch as the link I2 must be inverted and passed twice through the discs 26a and 26b before being in its final form. However, the device illustrated in Fig. 7 and hereinafterdescribed deforms a continuous passage of bimetallic members, in line with the teachings of my invention,

*with a maximum speed' and with aminimum amount of handling, and,. therefore, greatly increases the production of the bimetallic members.

By having the teeth 28 adjustable, it is possible to adjust and, control the curvature of the finished bimetallic member I2, and by having the disc 26b movable with respect to the disc 28a, the depth of thecrimping within the lateral 7 strips I6 may be adjusted. Accordingly, inas- Accordingly, it follows that, the adjusting plate Y and 88, respectively.

much as the fixed curvature of the bimetallic member I2 determines the operating or snapping temperature of that the operating temperatures of the bimetallic member may be adjustably varied by determining the fixed curvature thereof. In addition, inasmuch as the depth of the crimping deformationsin the lateral strips may be varied, itis likewise obvious that the lower and upper operating limits of the bimetallic member may be simultaneously varied. It is to be understood that these operations are performed at room temperature.

If it be desired to manufacture the bimetallic link I2 in a mass production process, a mechanical deforming device 54 (see Fig. 7) may be used. The device 54 comprises a supportingstructure 58, driving gears 58 and 60 operatively associated with the driving mechanism 58 anda suitable power supplying motor 58. The gears are rotatively attached to the supporting structure 58 by suitable pins 62 and may be formed of an upper and lower plate 64 The plates 64 and 66 have therein which tend to I6 of the-bimetallic link I2 in a predetermined manner, as hereinabove described. The teeth 68 are located in the upper plate'84 and directly below in the lower plate 68. According y. it is obvious that the link I2 may be fed through the gears 80 so that both lateral strips I6 may be simultaneously crimped. In addition, inasmuch as there is a gap between cooperating teeth 68 such member, it is obvious double deforming gears the upper and lower plates, the supporting rivet 20 may also be rigidly attached to the link I! before being associated with the device 54. Further, if desired, the link l2 may be partially punched from an elongated strip or blank I0, which in turn, may be inserted into the. gas 60 which will successively deform spaced link portions of the elongated strip. The links may then be severed one from another by a suitable operation.

The link I! after being formed at or about room temperature, substantially as hereinabove piece of composite thermostatic material to a form 'having a central strip and two lateral strips, and thereafter subjecting the lateral strips to separately adjustable mechanical deformations for producing a general curvature of the device and for determining the operating limits of such device.

. material, and thereafter heating the material 2. The method of manufacturing slotted thermostatic devices, which comprises cutting a piece of composite thermostatic material to a form having a central strip and two lateral strips, and thereafter subjecting the material to adjustable mechanical deformations for crimping the lateral strips to a preselected depth to determine the operating limits of the device and for producing a preselected degree of smooth curvature of such material to provide a pres'elect'ed operating temperature of the device.

3. The method of manufacturing slotted thermostatic devices, which comprises cutting a piece of composite thermostatic material to a form having .a central strip and two lateral strips, subjecting the lateral strips to mechanical deformations, and thereafter heating the material to a temperature above the normal working range of the device.

4. The method of manufacturing slotted thermostatic devices, which comprises cutting a piece of composite thermostatic material to a form having a central strip and two lateral strips,

subjecting the material to predetermined mechanical deformations for crimping the lateral. strips and for producing a curvature of such to a temperature above the normal working range of the device.

' PAUL R. LEE. 

